A gas turbine is a combustion engine. It usually comprises a compressor, a combustion chamber and a turbine. During the operation of the gas turbine, air is initially compressed by means of blading of one or more compressor stages, then mixed with a gaseous or liquid fuel in the combustion chamber, ignited and burned. The air is also used for cooling. Thus there arises a mixture of combustion gas and air, referred to as hot gas, which is expanded in the subsequent part of the turbine. During this process, thermal energy is converted into mechanical energy. This mechanical energy first of all drives the compressor, while the remaining part is used, in particular, to drive a generator. A gas turbine of this kind is shown in EP 2 128 406 B1, for example.
In the case of gas turbines in part-load operation, adapting the compressor intake air mass flow by setting variable compressor inlet guide blades is a known practice. It is thereby possible to achieve a maximum efficiency with a given maximum exhaust gas temperature. Here, the permissible minimum position of the variable compressor inlet guide blades is limited inter alia by cooling of the intake air in the region of the inlet guide blade row and/or the first compressor rotor blade row and the associated risk of icing. Depending on the humidity of the intake air, the acceleration of the flow downstream of the inlet guide blade row, which leads to cooling of the flow, may result in icing in the compressor and hence to impairment of the integrity of the machine and possibly to damage to the machine.